In spinal fusion surgery such as cervical vertebra fusion surgery, a method for embedding a pedicle screw in the spine is often used. The pedicle screw is embedded in such a manner that a pilot hole is formed beforehand by inserting a puncture instrument, such as a probe, and then the pedicle screw is screwed into the pilot hole.
However, in the vicinity of the spine, important organs, such as a spinal cord, a nerve root, blood vessels, and an internal organ, are located close to each other. Thus, when the position, at which the puncture instrument, such as the probe, is inserted to form a pilot hole in the cervical vertebra, is incorrect, serious damage may occur in the organs. Therefore, it is necessary to accurately determine the insertion position and direction of the puncture instrument.
Conventionally, the position of the vertebral pedicle, at which the probe is to be inserted, is checked from the front and side images of the spine captured by an X-ray apparatus, and then the probe is inserted without a guide. However, there is a problem that a variation occurs in the insertion accuracy according to the operator's experience and skills.
No technique for directly and accurately controlling the insertion position and direction of the probe has been disclosed. However, in relation to the technique, the present applicants have proposed a boring instrument guiding device which is used to form a pilot hole in a vertebral pedicle. The boring instrument guiding device is configured by including a reference pin that is used as a reference by being inserted into the vertebral arch from the posterior side to the anterior side of the spine, and an arm extending sideward from the proximal end side of the reference pin, and is configured such that a plurality of guide holes respectively opened toward the tip position of the reference pin to guide a boring instrument, such as an awl and a tap, are formed in the arm in a radial pattern (see Japanese Patent Laid-Open No. 2009-261485).
Further, in Japanese Utility Model Publication No. 3165179 different from Japanese Patent Laid-Open No. 2009-261485, there is proposed an insertion instrument guiding device for vertebral pedicle applications, which is used to more accurately guide the insertion position and angle of a pedicle screw when the pedicle screw is inserted into the vertebral pedicle. The insertion instrument guiding device is configured by including a fixed indication needle, a movable indication needle that is capable of adjusting the separation distance from the fixed indication needle, a reference line-positioning pin that is incorporated in a link mechanism so as to be positioned just at the midpoint of the separation distance between the needles, and an insertion guide section that sets and adjusts the insertion angle of the insertion instrument into the vertebral pedicle by being slid while maintaining a circular state with respect to the insertion position of the vertebral pedicle, the position being indicated by the fixed indication needle, and is configured such that, when the reference line-positioning pin is adjusted to the position of the spinous process, the insertion position and the insertion angle of the insertion instrument into the vertebral pedicle are guided with reference to the spinous process.
However, Japanese Patent Laid-Open No. 2009-261485 proposes the guiding device used in the case where an awl or a tap is used as a puncture instrument, and Japanese Utility Model Publication No. 3165179 proposes a guiding device which guides the insertion of a pedicle screw. Japanese Patent Laid-Open No. 2009-261485 and Japanese Utility Model Publication No. 3165179 both relate to important guiding devices for accurately guiding the insertion position and direction of a puncture instrument. However, there has been a request for a puncture instrument, such as a probe, which has a simple configuration formed by a metallic needle like an ice pick having a pointed tip, and which can accurately guide the insertion position and direction of the puncture instrument even when, without the use of the guiding device, a pilot hole is formed in a vertebral pedicle by using the puncture instrument.